An alternative definition has been developed of the delta scale of item difficulty used at Educational Testing Service. The traditional delta scale uses an inverse normal transformation based on normal ogive models developed years ago. However, no use is made of this fact in typical uses of item deltas. It is simply one way to make the probability…

False positive and false negative error rates were studied for competency testing when failing examinees are permitted to retake the test. Formulas are provided for the beta-binomial and Rasch models. Estimates based on these models are compared for six data sets from the South Carolina Basic Skills Assessment Program. (SLD)

Appropriateness measurement is a general approach to the problem caused by multiple choice tests failing to measure accurately the ability of atypical examinees. The conceptual framework of appropriateness measurement is presented, and several statistical indices of the appropriateness of a multiple choice test for an examinee are noted. A series…

Advantages and disadvantages of joint maximum likelihood, marginal maximum likelihood, and Bayesian methods of parameter estimation in item response theory are discussed and compared. (Author)